Direct-current and series-type dynamo electric machines utilize commutators, which have commutator segments embedded in an insulating bushing or insulating ring. The segments, usually, have a dovetailed end, located symmetrically to the axis of the commutator shaft, and include anchoring elements or devices. Commutators of this type, when used with an insulating body or bushing or insulating element which is free from asbestos may lose segments, at high-speed operation, due to the centrifugal forces acting on the insulation. This is particularly so if the commutators have many, and hence narrow segments, or are tiny; additionally, of course, the narrow tiny segments will result in tiny connecting ends to connect the commutator segments to the winding ends of the armature of the dynamo electric segments to the winding ends of the armature of the dynamo electric machine. It is difficult to fix, for example by welding, the ends of the windings to the segments or to the connecting ends in such a manner that the winding ends are reliably retained against centrifugal forces acting on the winding ends and/or the commutator segments during operation of the dynamo electric machine, and in such a manner that the insulation compound, filled into the gaps will not be interfered with. Therefore the insulation between the commutator segments must, additionally, be resistant to heat.